1. Field of the Invention
The present invention relates to technologies for quantifying features of spots included in an image.
More particularly, the present invention relates to technologies for quantifying features of spots in an image which includes a plurality of spots that correspond to genes or chromosomes labeled by fluorescent antibodies.
2. Description of the Related Art
In the medial field based on biotechnology, genes or chromosomes are labeled by fluorescent antibodies, and their aspects are observed in order to diagnose a variety of diseases represented by cancer.
Specifically, when genes or chromosomes labeled by fluorescent antibodies are observed with a microscope, the resulting image includes fluorescent regions (hereinafter referred to as “spots”) which correspond to these genes or the like. This image is digitized and captured into a computer which only detects spots corresponding to genes or chromosomes subjected to diagnosis, and quantitatively analyzes features of the detected spots, such as the size, shape and the like of the spots. Then, a doctor diagnoses diseases based on the quantified features of the spots.
For example, in a diagnosis of chronic myeloid leukemia, an important diagnostic index lies in the presence or absence of dislocation between carcinogenic gene c-abl on a ninth chromosome and a bcr gene on a 22-th chromosome. Accordingly, the presence or absence of dislocation is determined on the basis of a feature amount of spots corresponding to these genes, and a doctor makes a diagnosis.
While a laboratory technician can visually observe an image to detect spots corresponding to chromosomes subjected to diagnosis and quantify their features, this method is likely to depend on the laboratory technician's personal point of view and therefore implies problems in objectivity, reproductivity, and quantitativity. Thus, attempts have been made in diagnoses of diseases to automatically quantify features of spots in an objective manner on a computer.
A computer-based apparatus or method of quantifying features of spots involves finding a point at which the intensity (luminance) of a spot reaches a peak, setting n line segments centered at the peak point, finding n points at which the luminance presents predetermined value (th) for a luminance distribution of each line segment, minimal-elliptic-approximating an n-gon formed by connecting these points, and measuring the spot diameter, as disclosed in JP-H6-259784-A (Patent Document 1).
Also, as disclosed in JP-2004-535569-A (Patent Document 2), there is an apparatus or method which divides a region representative of a cell nucleus from the remaining region, and quantitatively analyzes a spot shape based on a luminance distribution of the divided region.
Here, when noise occurs, a computer reduces the noise by filtering with the use of a predetermined kernel in order to correctly perform a quantitative analysis, as disclosed in JP-2006-505782-A (Patent Document 3). Alternatively, as disclosed in JP-2006-084261-A (Patent Document 4), a computer sets a variable spot recognition region for recognizing one spot, and detects a spot based on a change in signal strength distribution when the size of the spot recognition region is changed, thereby suppressing the influence of noise.
However, the technologies described above have problems as shown below.
The apparatus or method disclosed in Patent Document 1 must perform a procedure for finding n points, and a procedure for minimal-elliptic-approximating an n-gon, in addition to a procedure for finding the peak of a luminance distribution, and a procedure for measuring features becomes complicated. Then, the method disclosed in Patent Document 3 must previously obtain a large number of experiment data for patterns of parameters contained in a region which represents a cell nucleus, and is therefore not a convenient method.
Also, the apparatus or method disclosed in Patent Document 3 or 4 fails to sufficiently suppress the influence of noise, and has a problem in which the quantitative analysis on features of spots is made incorrect due to noise and varying luminance.